1. Field of the Invention
The present invention relates generally to electronic displays and, more specifically, to electronic displays with conductive coatings.
2. Description of the Related Art
Many electronic displays have one or more optical coatings or thin films on a glass or similar substrate. Coating the surface of a display screen (e.g., glass) with a conductive material can provide shielding against electromagnetic interference (EMI) and radio frequency interference (RFI), sometimes collectively referred to as EMI/RFI shielding. For example, aircraft cockpit display screens are EMI/RFI shielded to minimize both emitted electromagnetic energy that might interfere with the operation of other instruments and impinging electromagnetic energy that might interfere with the operation of the display instrument itself.
Although a multitude of materials are known in the art for coating transparent optical substrates, the most common conductive material for coating display screens is indium-tin oxide (ITO). In addition to providing EMI/RFI shielding, ITO coatings are used for various other purposes, such as for electrodes in liquid crystal displays and heating and defogging elements in display screens and viewports. Such optical coatings are typically formed by vacuum sputtering or evaporation or similar well-known “thin film technology” methods. The term “thin film,” in the context of optics, is used in the art to refer to layers of material having thicknesses on the order of the wavelengths of visible light.
Ambient light reflecting off an EMI/RFI shielding coating hampers viewability of the display during daytime. Anti-reflective coatings are known and can be formed over the shielding (conductive) coating, but a conventional anti-reflective coating does not provide sufficient reflectivity reduction for demanding applications such as cockpit instrument displays. Accordingly, it would be desirable to provide a conductive coating structure for display screens that provides maximal EMI/RFI shielding with minimal reflectivity. It is to the provision of such a coating structure and method for making the structure that the present invention is primarily directed.